// HTMLParser Library $Name: v1_6 $ - A java-based parser for HTML
// http://sourceforge.org/projects/htmlparser
// Copyright (C) 2004 Somik Raha
//
// Revision Control Information
//
// $Source: /cvsroot/htmlparser/htmlparser/src/org/htmlparser/tags/ImageTag.java,v $
// $Author: derrickoswald $
// $Date: 2005/04/10 23:20:45 $
// $Revision: 1.49 $
//
// This library is free software; you can redistribute it and/or
// modify it under the terms of the GNU Lesser General Public
// License as published by the Free Software Foundation; either
// version 2.1 of the License, or (at your option) any later version.
//
// This library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
// Lesser General Public License for more details.
//
// You should have received a copy of the GNU Lesser General Public
// License along with this library; if not, write to the Free Software
// Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
//

package org.htmlparser.tags;

import java.util.Locale;
import java.util.Vector;

import org.htmlparser.Attribute;
import org.htmlparser.nodes.TagNode;
import org.htmlparser.util.ParserUtils;

/**
 * Identifies an image tag.
 */
public class ImageTag extends TagNode {
	/**
	 * The set of names handled by this tag.
	 */
	private static final String[] mIds = new String[] { "IMG" };

	/**
	 * Holds the set value of the SRC attribute, since this can differ from the
	 * attribute value due to relative references resolved by the scanner.
	 */
	protected String imageURL;

	/**
	 * Create a new image tag.
	 */
	public ImageTag() {
		imageURL = null;
	}

	/**
	 * Return the set of names handled by this tag.
	 * 
	 * @return The names to be matched that create tags of this type.
	 */
	public String[] getIds() {
		return (mIds);
	}

	/**
	 * Extract the location of the image Given the tag (with attributes), and
	 * the url of the html page in which this tag exists, perform best effort to
	 * extract the 'intended' URL. Attempts to handle such attributes as:
	 * 
	 * <pre>
	 * &lt;IMG SRC=http://www.redgreen.com&gt; - normal
	 * &lt;IMG SRC =http://www.redgreen.com&gt; - space between attribute name and equals sign
	 * &lt;IMG SRC= http://www.redgreen.com&gt; - space between equals sign and attribute value
	 * &lt;IMG SRC = http://www.redgreen.com&gt; - space both sides of equals sign
	 * </pre>
	 * 
	 * @return The relative URL for the image.
	 */
	public String extractImageLocn() {
		Vector attributes;
		int size;
		Attribute attribute;
		String string;
		String data;
		int state;
		String name;
		String ret;

		// TODO: move this logic into the lexer?

		ret = "";
		state = 0;
		attributes = getAttributesEx();
		size = attributes.size();
		for (int i = 0; (i < size) && (state < 3); i++) {
			attribute = (Attribute) attributes.elementAt(i);
			string = attribute.getName();
			data = attribute.getValue();
			switch (state) {
			case 0: // looking for 'src'
				if (null != string) {
					name = string.toUpperCase(Locale.ENGLISH);
					if (name.equals("SRC")) {
						state = 1;
						if (null != data) {
							if ("".equals(data))
								state = 2; // empty attribute, SRC=
							else {
								ret = data;
								i = size; // exit fast
							}
						}

					} else if (name.startsWith("SRC")) {
						// missing equals sign
						string = string.substring(3);
						// remove any double quotes from around string
						if (string.startsWith("\"") && string.endsWith("\"")
								&& (1 < string.length()))
							string = string.substring(1, string.length() - 1);
						// remove any single quote from around string
						if (string.startsWith("'") && string.endsWith("'")
								&& (1 < string.length()))
							string = string.substring(1, string.length() - 1);
						ret = string;
						state = 0; // go back to searching for SRC
						// because, maybe we found SRCXXX
						// where XXX isn't a URL
					}
				}
				break;
			case 1: // looking for equals sign
				if (null != string) {
					if (string.startsWith("=")) {
						state = 2;
						if (1 < string.length()) {
							ret = string.substring(1);
							state = 0; // keep looking ?
						} else if (null != data) {
							ret = string.substring(1);
							state = 0; // keep looking ?
						}
					}
				}
				break;
			case 2: // looking for a valueless attribute that could be a
					// relative or absolute URL
				if (null != string) {
					if (null == data)
						ret = string;
					state = 0; // only check first non-whitespace item
					// not every valid attribute after an equals
				}
				break;
			default:
				throw new IllegalStateException(
						"we're not supposed to in state " + state);
			}
		}
		ret = ParserUtils.removeChars(ret, '\n');
		ret = ParserUtils.removeChars(ret, '\r');

		return (ret);
	}

	/**
	 * Returns the location of the image.
	 * 
	 * @return The absolute URL for this image.
	 */
	public String getImageURL() {
		if (null == imageURL)
			if (null != getPage())
				imageURL = getPage().getAbsoluteURL(extractImageLocn());

		return (imageURL);
	}

	/**
	 * Set the <code>SRC</code> attribute.
	 * 
	 * @param url
	 *            The new value of the <code>SRC</code> attribute.
	 */
	public void setImageURL(String url) {
		imageURL = url;
		setAttribute("SRC", imageURL);
	}
}
